well its a bad opening. I don't know exactly what you require to call an opening 'refuted'...no, there is not some analysis which leads to a forced mate or anything...but anybody with eyes and some understanding of chess can see that it results in a weaker position than you should be striving for.
It would also probably surprise your opponents if you offer to give them pawn odds. It would certainly take them out of book. That doesn't mean its wise, of course.
Thanks for your comment. Well, I didn't meant 'refuted' literally, as in a forced mating line starting from move one... More in the sense of refuting an opening by playing the best lines. Therefore, I gave several examples of strong lines for black which can be seen as a sort of refutation. However, the average player will most likely not know how to 'refute' it.
I don't think the Grob is so bad as most people think. Some strong players advocate the opening. Offering your opponents to give them pawn odds is never a wise idea.
When being interviewed by New in Chess about a loss to Peter Svider as Black against Basman's Be2 Sicilian variation Kasparov retorted "We would never get any work done if we tried to prepare for everything" (or words to that effect)
That is why openings like the Grob will never fully die out and be consigned to the winds of time. Any opening is worth a try has long as you play it in the right circumstance against the right opponent.
I have just revised some of the old analysis of this post. It might be interesting to take another look!
At my level, it's not refuted at all, I play it quite often with mixed success. 
At my level, it's not refuted at all, I play it quite often with mixed success.
Exactly.
The thing about refutations, your opponents actually have to know them for them to be of any use.
A guy I know played the reversed Grob (...g5 on move one or two, with or without a preliminary ...h6) against Yermolinsky in a simul and drew. He had spent a couple of years studying and playing the Grob and was almost expert strength. I have played it in offhand games and it is rare that anyone has gotten an advantage off me although I haven't played it against masters--so I take the point someone made of it's having surprise value to have some validity, since although not good, 1.g4 is not utterly pointless, it tends to grab space, weakening and inefficient as it is, and until now amatuer players have not bothered to prepare for it.
At my level, it's not refuted at all, I play it quite often with mixed success.
Exactly.
The thing about refutations, your opponents actually have to know them for them to be of any use.
This.
I put it on SF 14, it considers it the worst possible first move. It gives black a -1.5 advantage. The second worst in Nh3, with a -0.9 advantage for black
The grob basically has one trap to justify its existence and the trap is good for black...
Grob to me is not as refuted as say, the Latvian, where if you put enough time into your study and are at least a decent class play should get winning positions everytime. Grob even if the computer thinks otherwise gives you playable if inferior positions, that only a pretty strong player with lots of prior analysis can refute.
Basmans whole chess career was showing how much you can could get away with. But he was also a fantastic player in general. But for me at least, any opening that clearly doesnt equalize for white is a no for me (if a white opening has like one or two obscure lines an engine may give -0.2 but is otherwise complex with mutual winning chances, i dont care, but grob gives black at least a slight plus in so many lines)
Recently I started playing Grob's Attack as a surprise weapon. It is a fun opening to play and it takes away the book knowledge to a certain extent, which you are ought to know for the main openings. There are also many dangerous traps that Black can fall into if he isn't prepared.
Let's take a look at some of these traps.